It is generally accepted that the Arctic is warming relative to the
rest of the world, in a process known as Arctic amplification.
Recent research suggests that, as a consequence, the jet stream
pattern is less geographically constrained but slower moving,
leading to extremes of hot and cold, wet and dry [1]. Also the NH
Hadley and Ferrel cells will have expanded with their boundaries
moving northwards [2abc].

I would assume the Arctic warming has thus affected the monsoons, to
make them less predictable with more frequent extremes. Can anybody
vouch for this?

BTW, I've come across another factor in Arctic amplification, which
is the extra IR absorption by CO2 at the pole [3]. This paper, from
2008 I would guess, gives a prediction of sea-ice-free September
2013!

Cheers,

John

P.S. Tietsche has done a grave disservice by suggesting the sea ice
will recover by itself, and it hasn't reached a tipping point [4].
But Tim Lenton, self-proclaimed expert on tipping points, now admits
that the sea ice may have already passed a crucial tipping point
[5].

"The study contains a stark warning about future weather
patterns, given projections showing that Arctic climate change is
likely to accelerate in coming years. “As the Arctic sea ice cover
continues to disappear and the snow cover melts ever earlier over
vast regions of Eurasia and North America, it is expected that
large-scale circulation patterns throughout the northern
hemisphere will become increasingly influenced by Arctic
amplification,” the study reports."

"Another study that is of
interest is the paper in Geophysical Research Letters, Recovery mechanisms of Arctic
summer sea ice, by S. Tietsche and colleagues.
This is a model study. With a model the scientist owns the world
and can prescribe what it looks like. In these numerical
experiments, the Arctic is prescribed with no ice. Then whether
or not the ice recovers is explored. In these studies the ice
does recover. The ocean does indeed take up extra heat in the
summer, but it gives it up quickly in the fall. This is followed
by the formation of first year ice in the winter. The ice-albedo
feedback that might let the ice melt runaway is limited.
Tietsche et al. conclude that it is not likely that Arctic sea
ice will reach a tipping point this century."